Feature Request: Built-in User Authentication / Password Protection for Web UI

### Feature Idea

Is your feature request related to a problem? Please describe.

Currently, when running ComfyUI with remote access enabled (e.g., using the --listen flag or running on a publicly accessible server), the web interface is accessible to anyone who knows the IP and port, as there is no built-in mechanism for user authentication or password protection. This poses a significant security risk for users who host their instance on a shared network or cloud environment.

Describe the solution you'd like

I propose adding a built-in, optional user authentication feature to the ComfyUI core. This could be implemented via:

Command-line arguments: E.g., --username and --password .

Configuration file: Allowing users to define one or more user accounts.

The feature should require users to enter credentials before accessing the main workflow interface.

### Existing Solutions

Currently, the recommended workaround is to use a reverse proxy (like Nginx or Caddy) to implement basic HTTP authentication. While effective, this requires additional software setup and technical knowledge, making it a barrier for less experienced users who simply need basic access control. A built-in feature would greatly simplify deployment and enhance security out of the box.

### Other

Implementing this would greatly improve the security and usability of ComfyUI for users running instances outside of a strictly local environment. Thank you for considering this feature!

Start by tracing how ComfyUI exposes the web interface when launched with --listen; the issue names no repository files or tests. Compare the requested built-in access control with the existing Nginx or Caddy workaround. Done would require an agreed optional authentication design, credential configuration, protected web access, and coverage for the relevant access paths.

Written by the indexing model from the issue text.